How Are Polymers Characterised?

Marine-grade plastics, non-stick Teflon, spiderweb silk and sheep’s wool are all examples of polymers. Made up of long chains of duplicated molecules, polymer materials can be both natural and synthetic. All polymers have different properties which affect their behaviour and determine suitability for applications. For example, some polymers boast exceptional strength while others offer great thermal stability.

These variations make polymer characterisation an important stage of product research and development. Scientists rely on a variety of polymer characterisation techniques to analyse polymer materials and determine properties such as molecular mass, structure, thermal stability and more. Data is used to educate decision makers and improve product performance.

We spotlight some of the most analytical methods for polymer characterisation below:

Chromatographic polymer characterisation

Chromatography, a laboratory technique used to split samples into individual components, is a gold-standard polymer characterisation method. A variety of techniques are used for polymer analysis, including highly specialised Gel Permeation Chromatography (GPC). Developed in the 1950s, the technique isolates analytes based on size. It’s a particularly useful method to calculate the molecular weight of polymers.

Thermal polymer characterisation

Of all the thermal analysis techniques used to characterise polymers, Differential Scanning Calorimetry (DSC) is one of the most useful. An article published in the Journal of Biometrical Techniques defines DSC as “a thermal analysis apparatus measuring how physical properties of a sample change, along with temperature against time. In other words, the device is a thermal analysis instrument that determines the temperature and heat flow associated with material transitions as a function of time and temperature.”

DSC data is a useful way to assess the various performance parameters of polymer materials, including crystallinity, thermal stability and the addition of additives such as stabilisers and flame retardants. Thermal analysis isn't used exclusively for polymer characterisation, with techniques also used to analyse petrochemical products. 

Spectroscopic polymer characterisation

Scientists often dive deeper into thermal analysis using spectroscopic techniques such as Dielectric Spectroscopy (DS). Also known as electrochemical impedance spectroscopy, the highly sensitive technique reveals more detail about temperature-driven transitions.

Near-Infrared (NIR) Spectroscopy is also one of the most popular analytical methods for polymer characterisation. The technique is useful for mapping the molecular structure of polymer materials, which can help improve product performance, reduce manufacturing costs and carry out quality control. NIR Spectroscopy is particularly sensitive to specific functional groups, including -OH, -CH and -SH. This makes the technique ideal for measuring parameters such as H2O content, acid number and amine concentrations.

Chromatographic, thermal and spectroscopic are just some of the polymer analysis techniques used at state-of-the-art laboratories. Find out more about complementary techniques, including microscopic, rheometric and mechanical polymer characterisation, in our complete guide, ‘Polymer Characterisation - Techniques, Types & Properties’.